/Engine/Plugins/Online/OnlineSubsystem/Source/Public/OnlineSubsystemFeatureFlags.h
Example application usage: REGISTER_ONLINE_SUBSYSTEM_FEATURE_RUNTIMECHECK(FRIENDS, FOnlineSubsystemFeatureCheck::CreateStatic(FParse::Param(FCommandLine::Get(), TEXT("EnableFriends")))
typedef TBaseDelegate_NoParams< bool > FOnlineSubsystemFeatureCheck